1. Field of the Invention
The present invention relates to an electric motor and more specifically to a disk drive apparatus provided with the motor.
2. Description of the Related Art
Conventionally, a spindle motor is mounted to a disk drive apparatus such as a hard disk drive. A conventional brushless motor disclosed in Japanese Patent Application Publication No. 2007-295666 includes an attachment plate, a bushing, a stator and a circuit board. The bushing is fitted to a fixing hole defined in the central area of the attachment plate. The stator is adhesively fixed to the outer circumferential surface of the bushing. Four coil wires of U-phase, V-phase, W-phase and neutral point are wound on a stator core of the stator. The circuit board makes contact with the axial upper surface of the attachment plate.
The circuit board includes a connecting land portion formed on the axial lower surface thereof. The attachment plate includes an axially-extending opening. At least a portion of the connecting land portion is axially overlapped with the opening and is exposed to the outside at the axial lower side. The end portions of the coil wires led out from the stator are soldered to the connecting land portion through the opening. Soldered portions are positioned higher than the axial lower surface of the attachment plate. As compared with a case where the coil wires are connected between the rotor and the attachment plate, it is possible to reduce the axial gap between the rotor and the attachment plate without having to take into account the thickness of the soldered portions and the contact of the coil wires with the rotor.
A conventional motor disclosed in “Background of the related art” section of Japanese Patent Application Publication No. H8-237899 includes a frame, coils and a power supply substrate. The frame includes an outlet hole in the form of a through-hole. The power supply substrate is arranged on the lower surface of the frame with an insulating body interposed therebetween. Passage holes are defined in the insulating body and the power supply substrate. The terminal ends of the coils are inserted through the outlet hole and the passage holes and are bonded by solders or the like to the conductive pattern formed on the lower surface of the power supply substrate.
In recent years, a demand exists for height reduction of a disk drive apparatus and also for height reduction of a motor. The height of solder on a substrate is usually about 1 mm. In the conventional motor of Japanese Patent Application Publication No. H8-237899, if an attempt is made to reduce the height of the motor, the solder is likely to protrude downward from the frame. In the conventional motor of Japanese Patent Application Publication No. 2007-295666, it is difficult to reduce the height of the motor because a thick wiring substrate is arranged on the upper surface of the attachment plate.